Production of 1,3-propylene diamine



United States Patent 3,223,735 PRODUCTION OF LS-PROPYLENE DIAMINEHeinrich Scholz, Ludwigshafen (Rhine), and Paul Guerrthert, Iggelheim,Pfalz, Germany, assignors to Badische Aniiin- & Soda-FabrikAktiengesellschaft, Ludwigshafen (Rhine), Germany No Drawing.Continuation of application Ser. No. 708,759, Jan. 14, 1958. Thisapplication Dec. 10, 1962, Ser. No. 243,651 Claims priority, applicationGermany, Jan. 23, 1957, B 43,227 8 Claims. (Cl. 260-583) Thisapplication is a continuation of application Serial No. 708,759, filedJanuary 14, 1958, which is now abandoned.

This invention relates to a process for the production of 1,3-propylenediamine. More specifically, the invention relates to a process for theproduction of 1,3-propylene diamine from acrylonitrile and ammonia bytreating the mixture of the initial materials at elevated temperaturewith hydrogen in the presence of hydrogenation catalysts.

It is known to prepare 1,3-propylene diamine by reaction of1,3-dihalopropane with ammonia or, according to the method of Gabriel,from N,N'-trimethylene-diphthalimide by the action of caustic alkalisolution. From Us. Patent No. 2,425,693 it is also known to reactalkoxypropionitriles with primary or secondary amines to formN-substituted fi-aminopropionitriles which can be hydrogenated to thecorresponding propylene diamines by known methods. If attempts are madeto arrive at 1,3-propylene diamine in a similar way, by reactingalkoxypropionitrile with ammonia and hydrogenating the reaction product,1,3-propylene diamine is not obtained because the reaction ofalkoxypropionitriles with ammonia does not yield aminopropionitrile buta condensation product of indeterminate composition. It is further knownthat 1,3-propylene diamine is obtained by reacting acrylonitrile witharmmonia to 1,3-aminopropionitrile and catalytically hydrogenating theaminopropionitrile formed in a second stage to 1,3-propylene diamine.This two-step process gives relatively low yields.

It is an object of the present invention to provide a process for theproduction of 1,3-propylene diamine which gives higher yields than theprior art processes. It is another object of the invention to provide aprocess for the production of 1,3-propylene diamine which is carried outcontinuously and in a single step.

We have now found that 1,3-propylene diamine is obtained in a continuousprocess in good yields by continuously mixing acrylonitrile with anexcess of liquid ammonia in a ratio of to 20 parts by weight of ammoniato 1 part by weight of acrylonitrile and continuously treating theliquid mixture with hydrogen at a temperature of from 20 to 200 C. andunder a pressure between and 500 atmospheres in the presence of ahydrogenation catalyst.

Suitable hydrogenation catalysts are the conventional hydrogenationcatalysts, e.g., metals of groups V-B, VI-B, VII-B and VIII of theperiodic system or compounds thereof, for example the nitrates,carbonates, hydroxides, oxides or sulfides, as Well as mixtures of thesame. Examples are vanadium, niobium, tantalum, chromium, molybdenum,tungsten, manganese or compounds thereof. Conventional mixedhydrogenation catalysts, as for example copper-chromium oxide catalysts,may also be used. It is advantageous to use metals of group VIII of theperiodic system, for example cobalt and/ or nickel or their compounds,especially the oxides of these metals. Copper may also be used ashydrogenation catalyst. The last-mentioned metals may also be used inthe form of Raney catalysts. The catalysts may be used alone or ap- "iceplied to carriers. As carriers for the catalysts there are suitable, forexample, alumina, the natural or synthetic silicates, silica gel, zincoxide, titanium oxide or magnesium oxide.

It is advantageous to subject the catalysts prior to the reaction to areducing treatment at elevated temperature, for example at 300 to 500C., and under increased pressure, for example at 50 to 350 atmospheres,in a stream of hydrogen. The catalysts may be rigidly arranged in thereaction chamber. They may however also be agitated in the reactionchamber or kept in turbulent motion by the fluidized bed principle inpowdery, granulated or pelleted form. The hydrogen necessary for thehydrogenation preferably serves for fiuidizing the catalysts.

In order to carry out the process, acrylonitrile and liquid ammonia in alarge excess are intimately mixed. The mixing may be carried out forexample in a tubular mixing device or nozzle. In this case theacrylonitrile and the liquid ammonia are led through two pipes arrangedat an angle through a nozzle into a larger pipe in such a way that theturbulence thereby produced effects thorough mixing of the twosubstances. About 5 to 20, advantageously 8 to 15, especially 12, partsby weight of liquid ammonia is used for each part by weight ofacrylonitrile. This large excess of ammonia is necessary in order tosuppress side reactions which lead to di-(w-cyanoethyD-amine and di-(w-aminopropyU-arnine. The mixture is then preferably heated to thereaction temperature, or to a temperature lying somewhat below the same,for example to 60 to C. One or both components may be heated prior tomixing. The liquid reaction mixture is then led over the catalysttogether with hydrogen.

The liquid initial materials may also be trickled downward over arigidly arranged catalyst and preheated hydrogen introduced into thereaction vessel in cocurrent or countercurrent at one or more places.

Hydrogen is used in an amount of 100, 500, 1000 or 3000 liters or more,especially 600 to 800 liters, per kilogram of liquid feed mixture.Instead of technical hydrogen, gases may be used which mainly containhydrogen provided they are free from catalyst poisons. In this caselarger amounts of these gases are necessarily according to the hydrogencontents. The reaction is carried out at a temperature of 20 to 200 C.,especially 50 to 150 C., advantageously 90 to C., and under a pressureof 15 to 500 atmospheres, advantageously at 50 to 400 atmospheres. Thereaction is preferably carried out continuously, and by a suitable feedrate the formation of high-boiling byproducts and the formation ofresidues, both of which are dependent in a high degree on the residencetime at the catalyst, are avoided.

The liquid reaction mixture leaving the reaction chamber is preferablyworked up immediately by fractional distillation. The fractionaldistillation is preceded by the separation of the hydrogen and theammonia or a part thereof, and this may be done either under thereaction pressure or after a partial decompression while utilizing theheat content. The procedure may be, for example, that any partlydissolved hydrogen present in the reaction mixture is first liberated.by partial decompression and returned into the hydrogen circulation,while the excess ammonia wholly or partly escaping at the same time isseparated after liquefaction by raising the pressure and used again formixing with acrylonitrile. In the subsequent distillation stage, theresidual ammonia is set free upon complete decompression. This can alsobe liquefied by pressure increase and separated.

The method according to this invention shows considerable advantages ascompared with the methods hitherto known. While in the reactionpf1,3-dihalopropanes with ammonia considerable amounts of useless ammoniumhalide .are obtained which must be removed from the reaction mixturewith great technical ditficulty, the reaction mixture obtained accordingto the process of the present invention can be Worked up in a simple wayby fractional distillation. The process aifords very high yields whichconsist for the most part of pure 1,3-propylene diamine which canreadily be separated from the di-(waminopropyl)-amine obtained as abyproduct. Both the 1,3-propylene diamine and also thedi-(w-aminopropyl) amine obtained as a byproduct are valuable products,for example for the surface coatings and rubber industries.

The following examples will further illustrate this invention, but theinvention is not restricted to these examples. The parts specified inthe examples are parts by weight.

Example 1 100 parts of acrylonitrile and 1,400 parts of liquid ammoniaare passed through a heated tube. The resultant reaction mixture heatedto 70 C. is led, together with a large excess of hydrogen, under apressure of 300 atmospheres and at a temperature of 85 to 105 C. througha vertical reaction vessel which is filled with shaped reduced cobaltoxide.

On distilling the reaction mixture under pressure, the excess ammonia isfirst recovered in liquid form and may be returned to the reaction. Uponfurther distillation at atmospheric pressure, pure 1,3-propylene diaminepasses over at 136 to 138 C. as the main product. Then followsdi-(w-aminopropyD-amine which boils at 95 to 97 C. at 3 mm. Hg. Thetotal yield of amine mixture, consisting of about 2 parts of1,3-propylene diamine to each part of di-(w-aminopropyl)-arnine, is 97%of the theoreti cal yield.

Example 2 By using 74.3 parts of acrylonitrile and 1,100 parts of liquidammonia and carrying out the reaction with hydrogen described in Example1 under a pressure of 220 atmospheres at a temperature of 100 to 110 C.,66.5 parts of 1,3-propylene diamine and 28.5 parts of di-(w-aminopropyl)-amine are obtained, i.e., about 95% of the theoretical yieldwith reference to the acrylonitrile used.

Example 3 8.2 parts of acrylonitrile per hour is led together with 110parts of liquid ammonia under a pressure of about 300 atmospheresthrough .a heated mixing device in which the reaction mixture ispreheated to 85 C. This mixture is then introduced continuously,together with hydrogen, into the lower part of a vertical reaction towerwhich is filled with reduced cobalt oxide pellets. The reactiontemperature is 90 to 110 C. In order to maintain this temperature,superheated hydrogen is led into the reaction tower at one or moreplaces. The product continuously leaving the upper end of the reactiontower is led through a heat exchanger into a separator from which theexcess hydrogen is withdrawn and recycled to the reaction. It isadvantageous to construct the mixing device as the heat exchanger inorder to utilize the reaction heat for heating the feed materials.

The liquid fraction is worked up as described in Example 1. 7.15 partsof pure 1,3-propylene diamine is obtained per hour besides 3.1 parts ofdi-(w-aminopropyD- amine, i.e., about 93% of the theoretical yield withreference to the acrylonitrile introduced.

Example 4 100 parts of acrylonitrile is led together with 1,400 parts ofliquid ammonia through a heatable tube. The reaction mixture heated to80 to 90 C. is led together with a large excess of hydrogen under apressure of 300 atmospheres and at a temperature of 95 to 110 C. througha vertical reaction vessel which has been pretreated under reducingconditions. This vessel is filled with a catalyst consisting of silicapellets of 4 mm. in diam 'eter onto which 25% of cobalt and 2 to 3% ofchromium Example 5 parts of acrylonitrile per hour is led together with1,200 parts of liquid ammonia through a heatable tube. The reactionmixture heated to 95 C. is led together with a large excess of hydrogenunder a pressure of 350 atmospheres and at a temperature of 95 to C.through a vertical reaction vessel which is filled with shaped reducednickel oxide.

The reaction mixture is worked up as set forth in Example 1. The yieldof amine mixture, consisting of about 2 parts of 1,3-propylene diamineto each part Of di-(w-aminopropyD-amine, exceeds 90% of the theoreticalyield.

We claim:

1. A continuous process for the production of 1,3- propylene diaminewhich comprises continuously mixing acrylonitrile with an excess ofliquid ammonia in a ratio of 5 to 20 parts by weight of ammonia to onepart by weight of acrylonitrile and continuously treating the liquidmixture with hydrogen at a temperature of from 20 to 200 C. and under apressure of between 15 and 500 atmospheres in the presence of ahydrogenation catalyst.

2. A process as claimed in claim 1, wherein 8 to 12 parts by weight ofliquid ammonia are used for each part by weight of acrylonitrile.

3. A continuous process for the production of 1,3- propylene diaminewhich comprises continuously mixing one part by Weight of acrylonitrilewith 5 to 20 parts by weight of liquid ammonia, continuously treatingthe liquid mixture with hydrogen at a temperature of from 20 to 200 C.under a pressure of between 15 and 500 atmospheres in the presence of ahydrogenation catalyst, recovering the excess of liquid ammonia bydistillation under pressure and subjecting the reaction mixture obtainedto fractional distillation after decompression.

4. A continuous process for the production of 1,3- propylene diaminewhich comprises continuously mixing acryclonitrile with an excess ofliquid ammonia in a ratio of 5 to 20 parts by weight of ammonia to onepart by weight of acrylonitrile and continuously treating the liquidmixture with hydrogen at a temperature from 20 C. to 200 C. and under apressure of between 15 and 500 atmospheres in the presence of ahydrogenation catalyst selected from the group consisting of copper andmetals of the 5th to 8th groups of the periodic system.

5. A process as claimed in claim 4 wherein 8 to 12 parts by weight ofliquid ammonia are used for each part by weight of acrylonitrile.

6. A process as claimed in claim 4 wherein nickel is the metal of thehydrogenation catalyst.

7. A process as claimed in claim 4 wherein cobalt is the metal of thehydrogenation catalyst.

8. A continuous process as claimed in claim 4 wherein the liquid mixtureis maintained at a temperature of about 50 C. to C. and a pressure ofabout 50 to 400 atmospheres.

References Cited by the Examiner FOREIGN PATENTS 122,479 10/ 1946Australia.

OTHER REFERENCES Whitmore et al.: J.A.C.S., vol. 66, pp. 725-31 (1944).CHARLES B. PARKER, Primary Examiner,

1. A CONTINUOUS PROCESS FOR THE PRODUCTION OF 1,3PROPYLENE DIAMINE WHICHCOMPRISES CONTINUOUSLY MIXING ACRYLONITRILE WITH AN EXCESS OF LIQUIDAMMONIA IN A RATIO OF 5 TO 20 PARTS BY WEIGHT OF AMMONIA TO ONE PART BYWEIGHT OF ACRYLONITRILE AND CONTINUOUSLY TREATING THE LIQUID MIXTUREWITH HYDROGEN AT A TEMPERATURE OF FROM 20* TO 200*C. AND UNDER PRESSUREOF BETWEEN 15 AND 500 ATMOSPHERES IN THE PRESENCE OF A HYDROGENATIONCATALYST.